1. Field of the Invention
The present invention relates to a voice-controlled apparatus such as a so-called automatic answering telephone having an automatic answering function.
2. Description of the Related Art
Some conventional automatic answering telephones have a function for receiving a push phone dial signal. With a telephone of this type, a user can make a telephone call to this telephone from an outdoor telephone to hear a recorded message. In this case, the user inputs an ID number (identification data) by depressing the push buttons on the outdoor telephone.
The ID number is converted to a DTMF (Dual Tone Multi Frequency) signal used as the push phone dial signal, and reaches the automatic telephone through the telephone line, where it is encoded. When the encoded DTMF signal coincides with a number registered in advance in the automatic answering telephone, the user can hear the recorded content.
In order to hear the recorded content, push buttons are depressed to designate a predetermined operation. For example, "1" designates a rewind operation; "2", a fast-forward operation; "3", a playback operation; and "4", a stop operation. The automatic answering telephone receives these DTMF signals and executes the designated function.
However, since the above operation functions are encoded by numerals, the user may tend to forget the correspondence between the operations and codes.
Thus, if each operation is designated by a voice or voice input (e.g., a word "rewind", "fast-forward", "playback", or "stop"), and the designated operation is recognized by the automatic answering telephone, the user can easily actuate the above operations.
In order to execute speech recognition with existing techniques, a voice level input to a speech recognition means must be appropriate. However, the level of a voice signal externally input through a telephone line varies considerably. Causes of the variation are mainly present in the state of the telephone line. More specifically, when the telephone line suffers from a large signal transmission loss, the level of the voice signal reaching the speech recognition means is decreased. However, when a user makes a local telephone call, the transmission loss on the telephone line is very small, therefore a high level voice signal can be input to the speech recognition means.
More specifically, when the telephone line is connected to the speech recognition means, the input level of a voice signal varies considerably depending on the state of the telephone line between the calling party and the speech recognition means. Therefore, this state is very disadvantageous for a speech recognition apparatus, and accurate speech recognition may not always be attained.